Texas Instruments PCA9544APWR

Overview

PCA9544APWR from Texas Instruments is a low-voltage, 4-channel bidirectional I²C/SMBus multiplexer with integrated interrupt logic and voltage-level translation capability. It enables one I²C master to selectively route SCL/SDA signals to one of four downstream slave buses, supports 1.8-V to 5-V bus translation, operates from 2.3 V to 5.5 V, features active-low interrupt inputs (INT3–INT0) and a shared active-low interrupt output (INT), and is used in server backplanes to resolve I²C slave address conflicts among identical temperature sensors.

For engineers reviewing the PCA9544APWR datasheet, PCA9544APWR pinout, PCA9544APWR application, or PCA9544APWR equivalent, this device is selected when system-level I²C bus expansion, fault-isolated channel switching, multi-voltage domain interoperability, and hardware-managed interrupt aggregation are required - not for general-purpose logic or power switching.

Technical Context

The PCA9544APWR implements a single 8-bit control register accessed via I²C to select exactly one of four downstream channels (SCn/SDn), with channel enable bits (B2–B0) and read-only interrupt status bits (INT3–INT0). Its switch architecture uses low-R_ON pass gates referenced to VCC, enabling bidirectional signal translation without level-shifter ICs.

Interrupt logic performs a wired-AND of INT3–INT0 onto the open-drain INT output, with internal filtering rejecting pulses shorter than 1 μs (low) or 0.5 μs (high). Power-on reset initializes all channels to deselected state and resets the I²C state machine when VCC rises above VPORR (1.5 V typ.) or falls below VPORF (1.0 V typ.).

Key Specifications

Pinout & Package

TSSOP-20 (PW) package: 6.50 mm × 4.40 mm body, 0.65 mm pitch, exposed thermal pad not present. Compatible with standard surface-mount reflow profiles and automated optical inspection.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar I²C multiplexer applications.

Compared with PCA9544APWR, PCA9548APWR adds channel count at the cost of footprint and routing overhead, while TCA9544APWR delivers identical functionality with superior ESD immunity in the same physical form - making it the preferred upgrade path where qualification timelines allow.

Availability

PCA9544APWR is available at Aetrix Electronics and suitable for server backplanes, telecom routers, and factory automation controllers requiring stable component supply, long-term obsolescence management, and traceable sourcing for industrial-grade deployments.

Supply support for PCA9544APWR includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Texas Instruments is a global semiconductor leader specializing in analog, embedded processing, and connectivity technologies, with decades of leadership in interface and power management ICs.

The PCA9544A belongs to TI's I²C infrastructure portfolio, designed specifically to solve bus contention, address collision, and multi-voltage interoperability challenges in dense, modular electronic systems.

FAQ

What is the maximum I²C clock frequency supported by the PCA9544APWR?

The PCA9544APWR supports I²C clock frequencies up to 400 kHz, compliant with Fast-Mode I²C specifications. This allows full compatibility with both Standard-Mode (100 kHz) and Fast-Mode peripherals without signal integrity degradation, provided bus capacitance remains ≤400 pF and pull-up strength is appropriately sized per channel.

Does the PCA9544APWR require external pull-up resistors on all I²C lines?

Yes, the PCA9544APWR requires external pull-up resistors on SDA, SCL, INT, and all SDn/SCn lines. Pull-up voltage must match the target bus domain (e.g., 3.3 V for upstream master, 5 V for downstream 5-V slaves). No internal pull-ups exist - omission causes non-functional I²C communication and undefined interrupt behavior on PCA9544APWR.

Can multiple PCA9544APWR devices share the same I²C bus?

Yes, up to eight PCA9544APWR devices can coexist on a single I²C bus using hardware address pins A0–A2. Each device must have a unique combination of A0/A1/A2 tied to VCC or GND; floating address pins are prohibited and will cause communication failure on PCA9544APWR.

How does the PCA9544APWR handle power-on initialization?

The PCA9544APWR incorporates an internal power-on reset circuit that forces all channels to deselected state and clears the control register when VCC rises above VPORR (1.5 V typical). This ensures predictable startup behavior and automatic recovery from bus lockups - no external reset signal is needed for reliable PCA9544APWR operation.

Is the PCA9544APWR pin-compatible with the TCA9544APWR?

Yes, the PCA9544APWR is pin-compatible with the TCA9544APWR in the TSSOP-20 (PW) package. Both share identical pinout, electrical characteristics, and functional behavior. The TCA9544APWR offers enhanced 4000-V HBM ESD rating but requires no PCB changes when substituting for PCA9544APWR.